Rickettsia africae an Agent of African Tick Bite Fever in Ticks Collected from Domestic Animals in Eastern Cape, South Africa.

Benson Chuks Iweriebor,Chikwelu Larry Obi,Ayabulela Nqoro

doi:10.3390/pathogens9080631

Benson Chuks Iweriebor, Chikwelu Larry Obi + Show 1 more

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https://doi.org/10.3390/pathogens9080631

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Abstract

Background: Ticks transmit a plethora of pathogens of zoonotic implications. Their distribution, diversity and the pathogens they transmit differ from one ecological location to another. Rickettsia africae is the agent of African tick bite fever found in South Africa, a zoonotic infection that is frequently reported among travelers who have visited many sub-Saharan African countries where the pathogen is prevalent. Methods: Ticks were collected from domestic animals in Raymond Nkandla Municipality, Eastern Cape, South Africa. The ticks were identified morphologically prior to DNA extraction followed by molecular identification of randomly selected ticks from the morphologically delineated groups. To assess for the presence of tick-borne pathogens belonging to Rickettsia spp. by PCR (polymerase chain reaction), we used specific primer pairs targeting the gltA, ompA and ompB genes. The selected amplified ticks, all positive ompB and forty three ompA amplicons were sequenced in a commercial sequencing facility. The obtained nucleotide sequences were edited and subjected to BLASTn for homology search and phylogenetic analyses were performed with MEGA 7 Version for genetic relationships with curated reference sequences in GenBank. Results: A total of 953 ticks collected in the study were delineated into three genera consisting of Amblyomma, Rhipicephalus and Hyalomma in decreasing order of abundance. The presence of rickettsial DNA was detected in 60/953 (6.3%) from the three genera of ticks screened. Genetic analyses of the DNA sequences obtained showed that they have phylogenetic relationship to members of the spotted fever group rickettsiae with R. africae, being the predominant SFGR (spotted fever group rickettsiae) detected in the screened ticks. Conclusion: This report shows that R. africae is the predominant spotted fever group rickettsiae in ticks collected from domestic animals in the study area and the human health impacts are not known.

Highlights

Tick-borne pathogens have been identified as the etiologic agents of emerging important human diseases especially in many tropical countries in Africa, Asia and South America [1]
Pathogens 2020, 9, 631 many recognized species of Rickettsia that are delineated into four major groups namely; the typhus group consisting of two species which are R. typhi and R. prowazekii, the spotted fever group which contains many species that are exclusively transmitted to humans through ticks bites, the transitional group comprising of R. australis, R. akari and R. felis that are associated with ticks, mites and fleas and the ancestral group made up of R. bellii and R. canadensis
The global distribution of tick-borne rickettsioses varies from one region to another as their geographical spread are determined by their tick vectors whose distributions are generally governed by suitable environmental conditions like relative temperatures, humidity and biotopes which varies from one region to the other [6,7]

Summary

Introduction

Tick-borne pathogens have been identified as the etiologic agents of emerging important human diseases especially in many tropical countries in Africa, Asia and South America [1]. Pathogens 2020, 9, 631 many recognized species of Rickettsia that are delineated into four major groups namely; the typhus group consisting of two species which are R. typhi and R. prowazekii, the spotted fever group which contains many species that are exclusively transmitted to humans through ticks bites, the transitional group comprising of R. australis, R. akari and R. felis that are associated with ticks, mites and fleas and the ancestral group made up of R. bellii and R. canadensis. Conclusion: This report shows that R. africae is the predominant spotted fever group rickettsiae in ticks collected from domestic animals in the study area and the human health impacts are not known

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